The present invention relates to apparatus for trimming uneven edges from drawn and ironed tubular metal bodies, such as aluminum or steel cans, and more specifically to an improved loading apparatus for supplying containers to the trimming station.
In recent years, a container known as a two-piece container has found a remarkable degree of success in the industry. This container is formed by drawing and ironing a flat metal blank into a tubular body having an end wall integral with one end of the body. An end panel is then connected to the free end of the tubular body.
In the manufacture of this type of container bodies, it is necessary to trim a portion of the free edge of the container body to produce containers of identical size as well as remove the uneven edge resulting from the drawing and ironing operation.
Numerous types of trimming apparatus have been proposed for performing this operation. Examples of such devices are disclosed in U.S. Pat. No. 3,425,251, issued Feb. 4, 1969 and U.S. Pat. No. 3,838,653, issued Oct. 1, 1974.
These trimming machines have found a remarkable degree of commercial success in the industry. In this type of machine, the container bodies are fed onto a mandrel or container supporting member by a plunger that is reciprocated between extreme positions through a cylinder and piston rod assembly. While this type of arrangement has proven successful, the apparatus requires complicated sensing mechanisms and a plurality of valves as well as pneumatic and electronic controls for controlling the movement of the plunger with respect to the remainder of the machine.
In order to simplify the construction and operatopm of this apparatus and reduce the cost of construction and maintenance, it is preferable that some other type of reciprocating mechanism be available. While fully mechanical systems for moving a plunger in a can trimming operation have been proposed, such as shown in U.S. Pat. No. 2,119,942, issued June 7, 1938, these types of units have not found any degree of commercial success because of some inherent problems. The system disclosed in this patent requires a complicated follower mechanism for moving the plunger relative to the frame. In addition, the speed of the unit is of necessity limited because of the large mass which is eccentrically positioned with respect to the drive shaft.